The present invention is directed to a support structure, particularly for use in a bridge structure, where a beam-like girder of steel reinforced concrete or prestressed concrete is supported on the upper ends of support piers so that it is bending resistant and, in addition, the girder is supported by a strut framework including diagonally extending compression struts of reinforced concrete.
Experience has shown where bridge roadway structures formed of prestressed concrete and spanning lengths of 250 m or more between supports and not supported by suspension members, such as in suspension bridges or cable-stayed bridges, that problems develop as compared to the methods developed and proven for smaller bridge spans up to 250 m. Such problems are especially noted when the bridge towers extending above the roadway, which permit the use of diagonal bracing, are to be avoided.
A strut framework is a static system which has been used in timber structures and has also found use in certain reinforced concrete structures. A strut framework is a type of truss in which the roadway girder spanning support piers is supported relative to the piers by diagonally extending compression struts of reinforced concrete extending between the girder and the pier. Such diagonal compression struts must be able to withstand axial compression loads in their long direction, and also bending loads as a result of the inherent dead weight of the strut. Accordingly, when the combination of bending loads are taken with axial loads, considering the buckling factor, the dimensioning of the strut becomes critical. Due to the dimensioning of such compression struts based on their loading, and in view of the requirements of reinforced concrete construction, the struts must extend relatively steeply from the roadway girder to the support pier with the result that the strut can not effectively increase the span length or the strut must be constructed with a large cross-section, in particular when viewed from the side of the bridge for absorbing the dead load bending moment. Accordingly, compression struts extending steeply from the roadway girder are not very effective and, furthermore, such struts with a large dimension as viewed from the side of the bridge, result in a considerable dead weight and have a disadvantageous effect on the aesthetic appearance of the bridge structure.